Halep, claiming her fourth title in seven tournaments, breezed past former Wimbledon champion Kvitova 6-2, 6-2 on the hardcourts at Yale University.
The 21-year-old Romanian improved to 35-14 this year, picking up momentum in the run-up to next week's Grand Slam event in New York.
The Czech Republic's Kvitova, meanwhile, came up short in her bid for an 11th career win and second of the year after taking the Dubai event in February.
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